Sharing my Sunnyvale CA garden, a 'potage du geek' kitchen garden of vegetables, herbs, and flowers for cutting, plus a potted fruit tree or two. A voyage of discovery, with tales of storm and shipwreck as well as treasure and glory.

Wednesday, October 17, 2007

A is for Avoiding Arsenic

We're starting a new series, the "Garden ABC". I thought we'd begin with a little scary information about ways that arsenic could be getting into your garden. That may sound bizarre, but actually arsenic is dangerous at very minor levels. The amounts to which we're exposed, from sources as diverse as coal-fired electrical plants to pressure-treated lumber to municipal water to chicken dinners, add up rapidly. Arsenic is a potent carcinogen, as well as a direct poison. The Safe Water Act would have lowered municipal water levels of arsenic from 50 parts per billion to 10 ppb, but it was struck down by the current administration.

Here in the USA, commercial chicken feed contains roxarsone, an organic (in the chemistry sense) arsenic compound that suppresses bacterial infections in the chickens' guts and makes them gain weight faster. Unfortunately studies are showing that it's secreted in the toxic, inorganic form. As one article so aptly put it, Food for Chickens, Poison for Man. It's banned in the EU and ought to be banned here.

The rate at which bacteria convert roxarsone to toxic arsenic has been widely underestimated until the recent publication of new evidence linking chicken litter and toxic arsenic. The chicken waste is pelletized and sold as fertilizer to commercial farmers. Chicken manure is also sold in dried or composted form at hardware and garden centers. Studies show that fields which are spread with this material are getting noticeable amounts of arsenic.